Medical devices have long utilized generally tubular elongated shafts wherein a distal end of a shaft is inserted within the body of a patient to a target site while a proximal end is manipulated by an operator and, in some cases, joined to an implantable device for delivery of therapy to the site. Such shafts are used in interventional devices, examples of which include infusion catheters, angioplasty catheters, electrical mapping catheters, and ablation catheters; and in conjunction with implantable devices, examples of which include drug infusion pumps, neurological stimulation devices and cardiac monitoring and/or stimulation devices, such as pacemakers and cardioverter defibrillators. Typically, the shafts include one or more elongated members functioning to facilitate diagnosis and/or deliver therapy; examples of such members include electrical conductors, fiber optic bundles, and drug delivery lumens. Additional elongated members are included in some shafts to facilitate steering of the shafts to a specific site within the body; examples of these members include stylet and/or guide wire lumens, pull wires and malleable rods. Embodiments presented herein exemplify a novel shaft construction for medical devices.